A vehicle is well known that includes an engine, an electric motor, and a clutch disposed on a power transmission path between the engine and the electric motor and capable of separating the engine from drive wheels. In such a vehicle, the engine is stopped while the clutch is released. Various techniques are proposed for starting the engine from such a state. For example, in a technique proposed in Patent Document 1, when a start of the engine is requested in a vehicle as described above, the clutch is slip-controlled to crank the engine by an output torque (synonymous with power and force if not particularly distinguished) of an electric motor so as to start the engine. In a technique proposed in Patent Document 2, at the engine start of a direct injection engine, fuel is injected and ignited in a cylinder of the engine stopped in an expansion stroke to increase an engine rotation speed by an explosion torque so as to perform a so-called ignition start.